Hello Abhimanyu
Engagement is a pledge for marriage which brings a new direction to one’s life. When we are going to write a letter on someone’s engagement, we must express our warm feelings and sentiments. It depends on the relation with the person to whom you are writing the letter to. The length of the letter depends on the relation with that specific person. The engagement letter needs to be presented in a proper way. It should create a good impact on the reader.
Here is an example of writing engagement letter,
[Date]
Dear [Name of the colleague or friend] and [his/her],
Congratulations! I am truly overjoyed to learn about your engagement. I am happy to know that you are getting married to a girl of your own choice. I am certain that you two will make an ideal couple. You are now committing yourself to a great responsibility and I wish you all success in sailing through it.